Winged Nazgûl flies over Edoras

'But [Sauron] said:... "We shall meet again soon. Tell Saruman that this dainty is not for him. I will send for it at once. Do you understand? Say just that!"'

Unfinished Tales, Part 4, Ch 3, The Palantíri

About an hour after midnight the fear fell on [Frodo, Sam, and Gollum] a third time, but it now seemed more remote, as if it were passing far above the clouds, rushing with terrible speed into the West.

'At dawn three days ago, lord,' [Dúnhere] said,... 'Gandalf brought tidings of your victory.... And then came the winged Shadow.'

'The winged Shadow?' said Théoden. 'We saw it also, but that was in the dead of night before Gandalf left us.'

'Maybe, lord,' said Dúnhere. 'Yet the same, or another like to it, a flying darkness in the shape of a monstrous bird, passed over Edoras that morning, and all men were shaken with fear. For it stooped upon Meduseld, and as it came low, almost to the gable, there came a cry that stopped our hearts. Then it was that Gandalf counselled us not to assemble in the fields, but to meet you here in the valley.... Naught has been seen in Harrowdale of these evil things.'